Viscoelastic-surfactant treatment fluids having oxidizer

Abstract

A method and reactive treatment fluid for treating a wellbore for filter cake removal, including providing the reactive treatment fluid having a viscoelastic surfactant (VES) into a wellbore in a subterranean formation and attacking the filter cake via the reactive treatment fluid.

What is claimed is: 
     
       1. A method of treating a wellbore for filter cake removal, comprising:
 providing a reactive treatment fluid comprising a viscoelastic surfactant (VES) into a wellbore in a subterranean formation to attack filter cake in the wellbore, wherein the reactive treatment fluid comprises:
 a reactive breaker comprising an oxidizing salt; and 
 an acid-generating material; and 
 
 attacking the filter cake via the reactive treatment fluid, wherein attacking the filter cake via the reactive treatment fluid comprises forming acid from the acid-generating material and attacking the filter cake with the acid. 
 
     
     
       2. The method of  claim 1 , wherein the filter cake is formed from solids in drilling fluid, and wherein attacking the filter cake comprises degrading the filter cake or dissolving at least a portion of the filter cake, or a combination thereof. 
     
     
       3. The method of  claim 1 , comprising delaying forming the acid from the acid-generating material in the wellbore, and wherein attacking the filter cake via the reactive treatment fluid comprises attacking the filter cake with the reactive breaker comprising the oxidizing salt. 
     
     
       4. The method of  claim 1 , comprising:
 specifying that the treatment fluid include the VES in response to the wellbore comprising a lateral, wherein the filter cake comprises polymer, and wherein the reactive breaker breaks the polymer; 
 gelling the reactive treatment fluid via the VES to give the reactive treatment fluid as a VES gel for retention of the oxidizing salt for breaking the polymer in the filter cake at an end portion of the lateral; and 
 flowing the reactive treatment fluid to the end portion of the lateral, wherein attacking the filter cake comprises breaking, via the oxidizing salt, the polymer in the filter cake at the end portion. 
 
     
     
       5. The method of  claim 1 , comprising:
 specifying inclusion of the VES in the reactive treatment fluid in response to the wellbore comprising a horizontal portion, wherein the reactive treatment fluid comprises a VES gel, wherein the filter cake comprises polymer, and wherein the reactive breaker breaks the polymer; and 
 flowing the reactive treatment fluid into the horizontal portion, wherein gelling performance of the VES gel promotes retention of the oxidizing salt in the reactive treatment fluid for breaking the polymer in the filter cake at an end portion of a lateral of the horizontal portion of the wellbore. 
 
     
     
       6. The method of  claim 1 , wherein the filter cake comprises a weighting agent from a drilling fluid, and wherein attacking the filter cake comprises dissolving the weighting agent with the acid. 
     
     
       7. The method of  claim 6 , wherein the reactive treatment fluid comprises a VES gel, and wherein forming the acid lowers viscosity of the VES gel. 
     
     
       8. The method of  claim 6 , comprising specifying an amount of the acid generating material in the reactive treatment fluid to generate acid in a range of 2 to 5 times a stoichiometric amount of acid in relation to the weighting agent for dissolving substantially all of the weighting agent in the filter cake, wherein the weighting agent comprises calcium carbonate, bentonite, barite, ilmenite, or manganese tetroxide, or any combinations thereof. 
     
     
       9. The method of  claim 6 , wherein forming the acid comprises forming the acid from the acid-generating material via heat from the subterranean formation. 
     
     
       10. The method of  claim 6 , wherein forming the acid comprises releasing the acid from the acid-generating material, wherein the acid-generating material comprises solid particles that degrade in the wellbore due to temperature of the subterranean formation to release the acid, and wherein particle size of the solid particles is in a range of 20 microns to 2 millimeters (mm). 
     
     
       11. The method of  claim 10 , wherein the acid-generating material comprising the solid particles comprise polylactic acid (PLA), poyglycolic acid (PGA), an orthoester, or polyanhydride, or any combinations thereof. 
     
     
       12. The method of  claim 11 , wherein the solid particles comprises polylactic acid (PLA) or poyglycolic acid (PGA), or both. 
     
     
       13. The method of  claim 6 , wherein the acid-generating material comprises an ester, and wherein forming the acid comprises hydrolyzing the ester to generate the acid. 
     
     
       14. The method of  claim 6 , wherein the acid-generating material does not comprise an ester that hydrolyzes to generate the acid, and wherein the acid-generating material does not comprise a polyanhydride. 
     
     
       15. The method of  claim 6 , wherein the acid-generating material comprises a combination of ammonium salt and the oxidizing salt, and wherein forming the acid comprises oxidizing ammonium of the ammonium salt with the oxidizing salt. 
     
     
       16. The method of  claim 15 , wherein attacking the filter cake comprises breaking polymer in the filter cake with the oxidizing salt, and wherein the reactive treatment fluid comprises the oxidizing salt at a concentration in excess of that to break the polymer. 
     
     
       17. The method of  claim 16 , wherein the oxidizing salt comprises bromate, and wherein the ammonium salt comprises a sulfonate-based ammonium salt or ammonium chloride, or both. 
     
     
       18. The method of  claim 17 , wherein the reactive treatment fluid comprises a lithium-based salt or a bromide-based salt, or combination thereof, as a delay agent causing an increase in induction time of acid generation by the acid-generating material that forms the acid. 
     
     
       19. The method of  claim 18 , comprising removing at least a portion of the filter cake from the wellbore via the attacking of the filter cake with the reactive treatment fluid, wherein the delay agent comprises lithium bromide (LiBr). 
     
     
       20. The method of  claim 6 , wherein forming the acid comprises releasing the acid from the acid-generating material. 
     
     
       21. The method of  claim 6 , wherein the forming the acid comprises releasing hydrogen ions (W) from the acid-generating material. 
     
     
       22. The method of  claim 6 , wherein the acid-generating material is neutral in the reactive treatment fluid at Earth surface prior to providing the reactive treatment fluid into the wellbore. 
     
     
       23. The method of  claim 1 , wherein the reactive treatment fluid comprises an inverting surfactant encapsulated in an encapsulating material that degrades at temperature of the subterranean formation, and wherein the filter cake comprises an oil-based filter cake formed from oil-based drilling fluid. 
     
     
       24. The method of  claim 23 , comprising:
 degrading the encapsulating material to release the inverting surfactant; and 
 inverting the oil-based filter cake with the inverting surfactant, wherein the inverting surfactant comprises an hydrophile-lipophile balance (HLB) of at least 12. 
 
     
     
       25. A method of treating a wellbore for filter cake removal, comprising:
 providing a reactive treatment fluid into a wellbore in a subterranean formation to attack filter cake in the wellbore, wherein the reactive treatment fluid comprises:
 a reactive breaker comprising an oxidizing salt to break polymer in the filter cake; 
 a viscoelastic surfactant (VES) to gel the reactive treatment fluid to give the reactive treatment fluid as a VES gel for retention of the oxidizing salt for breaking the polymer in the filter cake at an end portion of a lateral of the wellbore; and 
 an acid-generating material to form acid to dissolve a weighting agent from drilling fluid in the filter cake; 
 
 flowing the reactive treatment fluid to the end portion of the lateral; 
 gelling the reactive treatment fluid as the VES gel, thereby promoting retaining of the oxidizing salt in the reactive treatment fluid to the end portion of the lateral; 
 forming the acid via the acid-generating material; and 
 attacking the filter cake with the reactive treatment fluid. 
 
     
     
       26. The method of  claim 25 , comprising specifying an amount of the acid generating material in the reactive treatment fluid to generate acid in a range of 2 to 5 times a stoichiometric amount of acid in relation to the weighting agent for dissolving substantially all of the weighting agent in the filter cake. 
     
     
       27. The method of  claim 25 , comprising specifying that the treatment fluid include the VES in response to the wellbore comprising the lateral, wherein attacking the filter cake with the reactive treatment fluid comprises degrading the filter cake, dissolving the filter cake, or removing the filter cake, or any combinations thereof. 
     
     
       28. The method of  claim 25 , wherein attacking the filter cake with the reactive treatment fluid comprises:
 breaking the polymer in the filter cake with the oxidizing salt including at the end portion of the lateral; and 
 dissolving the weighting agent in the filter cake with the acid. 
 
     
     
       29. The method of  claim 28 , wherein the acid-generating material comprises solid particles comprising polylactic acid (PLA) or poyglycolic acid (PGA), or both, or wherein the acid-generating material comprises a combination of ammonium salt and a second oxidizing salt that oxidizes the ammonium of the ammonium salt to form the acid. 
     
     
       30. The method of  claim 29 , wherein the acid-generating material comprises the combination of the ammonium salt and the second oxidizing salt, wherein the second oxidizing salt comprises the oxidizing salt that breaks the polymer, and wherein the reactive treatment fluid comprises the oxidizing salt at a concentration in excess of that to break the polymer. 
     
     
       31. The method of  claim 29 , wherein the acid-generating material comprises the combination of the ammonium salt and the second oxidizing salt, wherein the ammonium salt comprises a sulfonate-based ammonium salt or ammonium chloride, or both. 
     
     
       32. The method of  claim 31 , wherein the reactive treatment fluid comprises a lithium-based salt or a bromide-based salt, or a combination thereof, as a delay agent causing an increase in induction time of acid generation by the acid-generating material that forms the acid. 
     
     
       33. The method of  claim 32 , wherein the delay agent comprises lithium bromide (LiBr).